This invention relates to a lid for a container neck provided with a thread or undercut shoulder and method of assembling same.
An undamageable lid for bottles, phials and similar vessels is known from German 1978 patent publication 27 00 322 which consists of one integral piece of synthetic substance. The lid has a safety ring joined to the main lid member by a ring shaped region of weak resistance which is likely to break from the pulling force during the first opening of the vessel. Since this lid consists of one single piece of synthetic material, production complications may occur, as the lid with its relatively rough form also encloses the delicate safety ring. Using an injection manufacturing process, this results in an inequality between the required injection times for the lid member itself and for the safety ring. Moreover, lids of synthetic material are not always suitable for bottle closures, especially for beverages having high carbon dioxide pressures. The more pressure tight metal lids are preferable for such beverage closures.
Indeed, metal lids are known, of which the lower edge is joined to a metal ring by way of joining strips, which break when the lid is unscrewed, so that the metal ring stays on the bottle neck. However, the disadvantage of such a lid is that after opening the metal lid and breaking of the joining strips, sharp metal edges may result, increasing the risk of injury for the user. Also, such metal lids are only applicable on container necks with small fabrication tolerances, because of the inflexibility of the dimensions of the metal lid.
A closure member for a container neck provided with a thread or undercuts is known from the French 1976 patent publication No. 22 91 915, comprising:
(a) a lid member having a protrusion to the outside at the lower edge, which is flanged to the inside in order to fit or acommodate; and PA1 (b) a ring of synthetic material comprising an upper part, joined to a lower part by way of a region of reduced resistance in the direction of the circumference, the upper part providing a ledge to fit into the protrusion of the lid. PA1 (a) a lid member (1), in particular of metal, having a protrusion (4) to the outside at the lower edge (3) in order to shape the inside to fit or accommodate; and PA1 (b) a ring of synthetic material (7) comprising an upper part (23), joined to a lower part (24) by means of a region (25) of reduced tearing resistance during opening of the lid in the direction of the circumference (12), the upper part (23) providing a protrusion to fit into the protrusion (4) of the lid member (1) and the lower part (24) providing a lip (26) protruding obliquely and inwardly towards the container neck shoulder. The outer protrusion at the upper part (23) of the ring (7) of synthetic material is in the form of a ridge (8) directed to the outside and the lower part (24) of the ring (7) of synthetic material has no protrusion to the outside so that the ring (7) has a substantially Z-shaped cross section. PA1 (a) a lid member (1), in particular of metal, providing a protrusion (4) to the outside of the lower edge (3) in order to shape the inside to fit PA1 (b) a ring (7) of synthetic material comprising an upper part (23), joined to a lower part (24) by means of a region (25) of reduced tear resistance during opening of the lid in the direction of the circumference (12), the upper part (23) providing a protrusion to fit into the protrusion of the lide member (1), in which at least the lower part of the ring (7) of synthetic material is arranged to be shrinkable.
Furthermore, the lower part of the ring has a lip, protruding obliquely inwardly in an upward direction to act against the shoulder of the bottle; on the outside of the lower part of the ring, however, a ledge, which supports itself against an outwardly flanged part of the lower edge of the lid member, is attached to this lip of the ring.
This double part arrangement of the lid permits the choice of material for the two parts to be independent of each other. Therefore, the lid or cap itself can consist of metal in particular, while the safety ring can comprise a synthetic material.
When unscrewing the lid, the outwardly protruding ledge of the upper part of the ring is supposed to support against the ring-channel-shaped flanged protrusion of the lower edge of the lid member, so that by means of a lever action of the ring ledge, the lower part of the ring is prevented from giving way to the outside; otherwise, the lip of the ring of synthetic material would give way at the outside of the shoulder of the container neck, preventing the upper and lower parts of the ring from tearing apart along the region of reduced resistance. Simultaneously, the metal lid or cap without the rigid, ring-channel-shaped flanged protrusion would experience an unevenly spread extension over its circumference. This is even more significant when the metal lid or cap with the ring of synthetic material is pulled over the container neck. A certain clearance between the ring, particularly the inwardly protruding lip, and the circumference of the container neck has to be maintained exactly because of this lever-like cooperation between the ledge and the edge of the metal lid or cap. With a lid or cap made entirely of synthetic material, which itself is already flexible, the conditions are even more unfavorable. This supporting ledge of the ring on the outside of the ring lip costs material. Moreover, the ring of synthetic material may also unintentionally be torn open at this point, as it protrudes over the edge of the lid member; this would erroneously indicate an opened bottle.
Compared with this, a one piece cap or lid of synthetic material is known from European 1981 patent publication No. 0 034 997. The safety ring of the lid can be shrunk by way of heat treatment to the container neck below the shoulder of the neck. However, such a lid or cap of synthetic material provides the same disadvantages mentioned above.
By contrast, the present invention provides a lid or cap with a separated safety ring of synthetic material, so that the materials of the lid member and ring can be chosen independently of each other. Moreover, the safety ring of synthetic material is not torn unintentionally before the lid is open.
Thus, a first embodiment of a lid for a container neck having a thread or undercut shoulder in accordance with this invention comprises:
With this construction, the safety ring of synthetic material has the form and effect of a grapple hook. This ensures tearing of the ring when opening the lid. Thus, it does not matter that the ring of synthetic material is a bit larger than the container neck, so that it can be pulled over the neck without much effort. Also material is saved, as there is no voluminous outer ledge provided for the ring at the lower part thereof. As this outer ring ledge is omitted, there is no possibility of tearing the ring unintentionally before the lid is opened.
An alternative construction for a lid for a container neck having a thread or undercut shoulder in accordance with this invention comprises:
With this construction, it is not necessary to provide a lip at the lower part of the ring, protruding obliquely inwardly in an upward direction. That is, by heat-shrinking of the ring, a particularly tight form hugging enclosure of the container neck with thread or undercut, especially below the neck shoulder, is achieved by the ring and, optionally, also by the lid. It may be added that a heat-shrinkable ring of synthetic material means, in particular a ring, is already known per se from the previously mentioned European patent publication and the state of the art described therein. Additionally, the protrusion of the lid can be arranged to be heat-shrinkable. Furthermore the lid itself can, if necessary, consist of heat-shrinkable synthetic material. Thus, a particularly reliable enclosure of the container neck can be achieved.
It stands to reason that, if necessary, with a construction according to the first embodiment described above, the safety ring and/or the protrusion can be arranged to be shrinkable. Moreover, at least the lower part of the ring and, if necesary the protrusion of the lid, can additionally be arranged to be shrinkable. In that case, exceptionally large tolerances of the container neck can be provided for.
Further saving of material, with little effect on the rigidity of the safety ring and a decrease of the clearance when the safety ring is pulled over the container neck, can be obtained with a ring of synthetic material arranged wherein the lip at the lower part of the ring is provided with teeth which fit into a corresponding groove of the lower part of the ring on the side of the lip. Thus, the lip can give way even more to the outside into the outer lower part of the safety ring. Consequently the lip can give way even better to the container neck, particularly to the neck shoulder. Unintentional destruction or tearing of the safety ring, especially when being pulled over the container neck, thereby becomes more unlikely. If the lower part of the ring of synthetic material is also arranged to be shrinkable, the lip can be enclosed by the outer, lower part of the shrinking process, resulting in a practically integral lower part.
A ring of synthetic material, with weakening lines at the lower part of the ring spaced at regular intervals transversely to the circumferential direction, is preferred in all cases. Thus, the ring can break over its entire circumference and fall down from the container neck. Consequently, the lower part of the ring is prevented from staying on the container neck and saves the trouble of removing the ring afterwards, before refilling of the container.
The region of reduced resistance between the upper and the lower part of the ring of synthetic material can be formed by providing joining strips or bridges, alternately interrupted by fractures in the ring of synthetic material. Preferably, the joining strips can be arranged in the upper third and the fractures in the lower third of the ring. The weakening lines can be arranged to have V-shaped cross sections, thus without the provisions of gaps or regions of removed material.
A problem which is always possible with the previously mentioned lids is that the ring of synthetic material is not completely torn off the lid. When one then puts the lid back onto the container neck, it is possible to push the broken lower part or parts of the ring, which have remained attached to the upper part, upwardly to the upper part of the ring immediately beneath the lower edge of the lid. Thus, it would not be obvious from the lower part of the ring of the lid, which is visible from the outside, that the ring is torn open; i.e., that the container has been opened already. In order to prevent such a deception, the ring of synthetic material can be arranged in a way in which, scattered over the region of reduced resistance, at least one support bridge is arranged transversely to the circumferential direction in order to join the upper and lower parts of the ring. The lower part has at least one weakening line arranged transversely to the circumferential direction of the ring. With this arrangement, a special assembly method is also necessary, which will be described in detail later on.
The technique, wherein there are a plurality of support bridges and a weakening strip provided adjacent one of the support bridges, is further preferred. The special effect of this technique will also be explained later on.
If the ring of synthetic material is formed having the lip with at least scattered elongations, an assurance against deception is given sufficiently by the ordinary assembly method of positioning the lid around the ring and then flanging the surrounding edge of the lid around the outwardly directed ridge of the ring. The elongations of the lip will push away the torn open parts of the lower part of the ring to the outside of the container neck, especially the protruding region. Therefore, at least a few parts of the lower part of the ring spread out and cannot be bent back to the container neck and to the lower edge of the lid or cap.
In the above assembly method wherein the protrusion of the ring is inclined or slanted inwardly in the upward direction along the entire ring circumference, the upper part of the ring of synthetic material is stressed inside the protrusion of the lid, resulting from the incline of the protrusion. If the lower part of the ring is now torn open along a weakening line, transverse to the direction of the circumference, support bridges between the upper and lower part will spread out from the container neck as a result of the stress in this region of the lower part of the ring. Then, it is no longer possible to push the broken parts of the ring to the inside and up, beneath the lid. This stressing by the incline of the protrusion can be obtained by way of the above assembly method in which the inwardly flanged lower edge of the lide is pressed upwardly so that the protrusion is pressed upwardly from the bottom in a certain way. The protrusion attempts to give way to this pressure by extending in the region of the lower edge, while the diameter of the protrusion in its upper region is pressed together, i.e., it collapses inwardly. Consequently, the protrusion obtains an incline to the inside and upwardly over its circumference.